1. Field of the Invention
This invention relates to a thermal engine system and in particular, to a thermal engine system utilizing a double-acting piston-cylinder arrangement to convert heat to mechanical energy.
2. Description of the Prior Art
Recently, attention has been directed to the necessity of more efficiently utilizing available energy sources. As a result, interest and activity has been focused upon the utilization of waste heat energy, such as that now lost in the effluent stack gases from all types of commercial and industrial furnaces, including conventional fossil fuel power generation plants or the heat energy present in cooling fluids, such as water, at the outlet of nuclear fuel power generation stations. Alternately, naturally occurring sources of heat, such as geothermal heat energy or solar energy, may be utilized as suitable energy sources. It has been suggested that this heat energy, which is presently being wasted or not efficiently utilized, can generate useful work. It is appreciated with regard to several of the above mentioned heat sources, since no benefit is presently being derived from much of this waste heat, any conversion thereof into useful work enhances the overall power output of the facility producing that waste heat.
It is advantageous therefore to provide a thermal engine system acting to convert waste heat to useful work with a predetermined level of efficiency so that the energy heretofore totally wasted may be utilized to generate useful work. Also, it is advantageous to provide a thermal engine system acting to convert naturally occurring geothermal or solar heat energy to useful work. It is also advantageous to provide a thermal engine system utilizing the waste heat energy of a power generating station in order to cause thermal expansion and contraction of a thermally responsive expansible member. It is of further advantage to utilize the thermally induced movement of the expansible member to reciprocate a piston disposed within a cylinder in a double-acting manner so as to alternately pressurize a working fluid disposed in first and second regions within the cylinder. It is of still further advantage to provide a float pressured accumulator or like storage element to store pressure energy transmitted to the working fluid and utilize that stored energy to do useful work. It is also advantageous to indirectly couple a thermally responsive expansible member with one or a plurality of double-acting piston-cylinders through suitable lever arrangements to utilize displacements of the expansible member to pressurize a working fluid disposed in each cylinder.
It is noted that it is well known to utilize expansion of expansible members to convert heat energy to generate motion of associated elements. For example, U.S. Pat. No. 170,447 (Muskov), U.S. Pat. No. 348,841 (Hainley), U.S. Pat. No. 1,134,147 (Miller), U.S. Pat. No. 3,699,769 (Bondurant), and U.S. Pat. No. 3,803,845 (Dennis), all disclose thermal engines which utilize the expansion of a thermally expansible member to cause motion of associated mechanical elements. In U.S. Pat. No. 3,291,054 (McKenzie), electrical energy is utilized to rectilinearly expand a thermally responsive expansible member to drive a single-action piston.